An MRAM (magnetic random access memory) chip employed as a nonvolatile semiconductor storage uses a magnetoresistive element as a storage element. The magnetoresistive element has a structure in which a tunnel barrier layer (non-magnetic layer) is sandwiched between a storage layer (magnetic layer) and a reference layer (magnetic layer). In addition, data is stored in parallel (same) or anti-parallel (opposite) magnetizing directions in the storage layer and the reference layer.
Recently, writing of data, i.e., magnetization reversal in the storage layer has been generally executed in what is called Spin Transfer Torque (STT). In addition, data has been read by passing a perpendicular current to a film surface in a multilayered structure of the magnetoresistive element. Directions of residual magnetization in the storage layer and the reference layer are perpendicular to the film surface (i.e., perpendicular magnetization) or parallel to the film surface (i.e., in-plane magnetization).